To determine the absorption characteristics of another drug, ranitidine, which was shown in the early development work to have poor bioavialability when a sustained release formulation was administered. For this study a 4.5 meter multilumen tube was designed. This tube allowed for the direct instillation of the injectable formulation of the drug into the stomach, jejunum, and cecum. With timed blood sampling, the pharmacokinetics of the drug were determined after each dose.